lfric_atm clim_gal9 does not always bit compare across nrun/crun boundary

### Version

main

### Are there any linked Issues or Pull Requests?

_No response_

### What happened?

At 3.1 + branch from PR383 (which fixes checkpointing for clim_gal9 when compiled with 64-bit precision), the NRUN/CRUN 64-bit test passes when checkpointing at timestep 4, but diverges when checkpointing at timestep 3.

(See #389 for issue with checkpointing when compiled with 32-bit `r_def` precision)

### Relevant log output

```shell

```

Start by reading PR383 and issue #389 for the existing checkpointing context, then reproduce the clim_gal9 NRUN/CRUN 64-bit test with checkpoints at timesteps 3 and 4. Compare the divergent results and identify the checkpoint/restart behavior that prevents a bit comparison from passing at timestep 3.

Written by the indexing model from the issue text.